Limits the minimum and maximum level of transparency.
Any level of transparency outside the defined range will be cropped to the closest limit inside the range.
The "Transparent" and "Opaque" are linked together; if you move
either beyond the other, both will move.
"Transparent" can never be greater than "Opaque".
Set the minimum level of transparency.
Range 0% to 100%, 0% means no lower limit.
Set the maximum level of transparency.
Range 0% to 100%, 100% means no upper limit.